Sea ice and primary production proxies in surface sediments from a High Arctic Greenland fjord: Spatial distribution and implications for palaeoenvironmental studies

Abstract

In order to establish a baseline for proxy-based reconstructions for the Young Sound–Tyrolerfjord system (Northeast Greenland), we analysed the spatial distribution of primary production and sea ice proxies in surface sediments from the fjord, against monitoring data from the Greenland Ecosystem Monitoring Programme. Clear spatial gradients in organic carbon and biogenic silica contents reflected marine influence, nutrient availability and river-induced turbidity, in good agreement with in situ measurements. The sea ice proxy IP25 was detected at all sites but at low concentrations, indicating that IP25 records from fjords need to be carefully considered and not directly compared to marine settings. The sea ice-associated biomarker HBI III revealed an open-water signature, with highest concentrations near the mid-July ice edge. This proxy evaluation is an important step towards reliable palaeoenvironmental reconstructions that will, ultimately, contribute to better predictions for this High Arctic ecosystem in a warming climate.

Linking the Modern Distribution of Biogenic Proxies in High Arctic Greenland Shelf Sediments to Sea Ice, Primary Production, and Arctic‐Atlantic Inflow

“…A change in the dominant groups of palynomorphs in this region as well as the δ 13 C, δ 15 N, and C:N signature of the organic matter also points to a lower salinity. This is consistent with observations from Ribeiro et al (), Xiao et al (), and Hörner et al (), where low sedimentary IP 25 concentrations were linked to reduced salinities. IP 25 is produced in the ice and released when the sea ice melts, in contrast to HBI III, which is thought to be produced in open waters by diatoms possibly blooming near the marginal ice zone (Belt et al, ), although not exclusively (Belt et al, ).…”

“…Biogenic Silica (BSi) concentrations varied Journal of Geophysical Research: Biogeosciences 10.1002/2017JG003840 between 0.45 and 4.96 mg g À1 dry mass Si (average 1.89 mg g À1 ) ( Figure 4a and Table 3), corresponding to 0.17 to 1.06 wt % SiO 2 (average 0.40 wt % SiO 2 ). These values are low in comparison with measurements from other high-Arctic fjord regions such as the Young Sound-Tyrolerfjord, where the average value is almost 3 times higher (Ribeiro et al, 2017). This can likely be explained by a longer lasting sea ice cover in the study area, with less biogenic silica accumulating on the seafloor as the result of reduced marine productivity.…”

“…It was recently suggested that studying IP 25 with its close relative HBI III (triene), likely produced by diatoms blooming in the marginal sea ice zone (Belt et al, ), allows for more precise information on past sea ice dynamics (Belt et al, ; Smik et al, ). However, so far relatively few studies have investigated the use of these proxies in fjord and coastal environments (Brown et al, ; Ribeiro et al, ).…”

Spring Succession and Vertical Export of Diatoms and IP25 in a Seasonally Ice-Covered High Arctic Fjord

“…Downcore changes in the sedimentary IP 25 concentrations from a given location are therefore typically interpreted to reflect temporal fluctuations in the sea-ice conditions. However, recent studies have shown that the sedimentary concentrations of IP 25 in coastal areas influenced by freshwater runoff are lower than expected, thus showing a mismatch with overlying sea-ice cover extent (Xiao et al, 2013;Hörner et al, 2016;Ribeiro et al, 2017;Limoges et al, 2018). Despite the growing number of IP 25 -based sea-ice reconstructions, only a limited number of studies have, to date, investigated the ecophysiological and environmental parameters that determine IP 25 production (e.g., Brown et al, 2011Brown et al, , 2014, raising concerns about the interpretation of IP 25 as a quantitative indicator of seaice cover, and the possible limitations to its application in the Arctic (Belt and Müller, 2013).…”

The Late Mesozoic‐Cenozoic Arctic Ocean Climate and Sea Ice History: A Challenge for Past and Future Scientific Ocean Drilling

“…The same consequence applies to totally ice-free conditions where no ice algae live, that is, IP 25 = 0. This difficulty in interpreting IP 25 data can be overcome by the additional use of phytoplankton-derived, open-water biomarkers such as brassicasterol and dinosterol (Müller et al, 2009(Müller et al, , 2011 or specific tri-unsaturated HBIs (Belt et al, 2015(Belt et al, , 2019Limoges et al, 2018;Ribeiro et al, 2017;Smik et al, 2016). By combining the environmental information carried by IP 25 and the different phytoplankton biomarkers (Figure 6c), even more semiquantitative estimates of present and past sea-ice coverage, seasonal variability, and marginal ice zone situations are possible (Müller et al, 2011;Belt et al, 2015Belt et al, , 2019Stein et al, 2017; for recent and critical review of this biomarker approach, see Belt, 2018).…”